Rotational zones and forces and moments

I’m working on a propeller and I need a rotating zone, for this to work it appears (from the tutorials I’ve followed) that I need to apply a cell zone to the surfaces of the cylinder that form the MRF rotating zone. However, that then means that when I try to run the simulation to determine the forces and moments there’s an error message:

Found a result control with faces that do not belong to the mesh: face 9@Cylinder, face 2@Cylinder, face 15@Cylinder. This may happen if the faces belong to a cell zone. Please remove these faces from the result control.

Removing the faces to fix the error leads to the error:

A multi-region mesh was assigned - this analysis-type requires a single-region mesh. Learn more.

One of the tutorials I’ve looked at (SimScale Login) seems to have a rotating zone without setting up the cylinder as a surface but I don’t understand how?

How can I have both a rotating zone and use forces and moments to get the data I need?

Perhaps, this documentation can help resolve the issue: Error: Result Control Assigned to Non-Assignable Face | SimScale

It appears that under Result Control in your project, the saved selection “rotations” includes ‘face 9@Cylinder, face 2@Cylinder, and face 15@Cylinder’.

Perhaps, one workaround that may be worth trying is to remove those three faces (‘face 9@Cylinder, face 2@Cylinder, and face 15@Cylinder’) from your saved selection “rotations” so that they are not included under Result Control. (This can be done by creating a new saved selection and selecting the parts of the propeller without the MRF rotating zone faces, which is named “Cylinder” in your project.)
Under Advanced Concepts, however, there should still be the MRF rotating zone assigned (which is named “Cylinder” in your project).

As an example, note in this tutorial project what faces make up “Runner Blades”, what faces are used in “Result Control” and what faces make up MRF rotating zone: Fluid Flow Through a Water Turbine | Tutorial | SimScale

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